Process for making diethoxyphosphoryl tetramethyldiamidothiophosphate



' PROCESS FOR MAKING DIETHOXYPHCSPHCRYL TETRANIETHYLDIANHDOTHIOPHOSPHATEGeorge A. Saul, Nitro, W. Va., assignor to Monsanto Chemical Company,St. Louis, Mo., a corporation of Delaware No Drawing. Application May 3,1954,

Serial No. 427,351

1 Claim. (Cl. 260-461) /CHs N 021150 S/ t o l CH ctmo 3 In co-pendingapplication Serial No. 256,365, filed No-' vember 14, 1951, is describeda method for preparing unsym. dialkyl bis(dialkylamido)pyrophosphatescomprising heating together substantially equimolecular proportions ofdiethyl chlorophosphate and the methyl or ethyl ester ofbis(dimethylamido)phosphoric acid.

In accordance with the present invention it has been found that themethyl or ethyl ester of bis(dimethylamido)thiophosphoric acid reactsimilarly to produce the aforesaid new compound.

The following is illustrative of the invention:

Into a 500 cc. flask equipped with stirrer, thermometer, and refluxcondenser topped with calcium chloride tube were charged substantially38.6 parts by weight (0.197 mole) ethyl bis(dimethylamido)thiophosphateand substantially 34.0 parts by weight (0.197 mole) of diethylchlorophosphate. The mixture was then heated to 120-l25 C. and held atthat temperature with stirring for 4 /2 hours, at which time the weightloss was 8.4 parts by weight. After standing overnight, the mixture wasagain heated for 3 hours under line vacuum and then under pump vacuum.At this time the total weight loss was 11.8 parts by weight. The mixturewas again heated for a 1 hour period during which time the temperaturewas maintained at about 120 C. under full pump vacuum. After this lastheat treatment the weight loss amounted to 12.8 parts by weight, thetheoretical weight loss for this reaction. The product, a yellow liquid,was filtered through Attapulgus clay to clarify. It analyzed as follows:

Found Theory Phosphor 20. 4 20. 4 Sulfur 9. 7 10. 8. 9 9. 2 l. 4761United States PatentO,

"" 2,729,668 Bat nted Jan- 3 1. 56

' z v I distillate obtained in 82.2% yield. Analysis of the product gaveA Found Theory Chlorine 19. 8 19. 0 Phosphorus 16. 0 16. 6 2o Sulfur 16.8 17. 1

The new compound is a potent insecticide. For example,diethoxyphosphoryl tetramethyldiamidothiphosphate gave 100% kill whenevaluated by the residue sprayed Petri dish test. Petri dishes weresprayed with an acetone solution of the test material usingapproximately 20 ml. for each spraying. The open dishes were held for 24hours, then the insects were placed on the dishes an'd held uncoveredfor 48 hours at room tem- Similarly, complete'kill withdiethoxyphosphoryl tetramethyldiamidothiophosphate was obtained whenused as a systemic insecticide. Bean plants in the second leaf stagewere cut and placed in 10 p. p. m. solutions of the new compound forthree days. The plants were then transferred to water and the organismstransferred to the plants. The toxic eflect of the diethoxyphosphoryltetramethyldiamidothiophosphate on insects feeding on such plants isshown in Table II. Table 11 Percent Kill at Concentration of- InsectSouthern Arm Worm 40 Two-spotted ite 100 100 Mexican Bean Beetle Larvae100 Application as a foliage spray was likewise eifective. An aqueousspray of diethoxyphosphoryl tetramethyldiamidothiophosphate was appliedto potted plants, some of which were infested with insects and some towhich insects were later transferred. Both surfaces of the foliage weresprayed to run-01f. After three days the 3 kill of the two-spotted mitewas 100% at dilutions of 0.1%, 0.05% and 0.25%. The effectiveness ofthis compound against leaf chewing insects is noteworthy. Unsyrn.diethyl tetramethyldiamidopyrophosphate and diethoxythiophosphoryltetramethyldiamidophosphate are inactive against these organisms.

Insecticidal properties are retained by compounds in which the ethyl andmethyl substituents are replaced by other short chain alkyl groupsnotably of 14 carbon atoms.

It is intended to cover all changes and modifications of the examples ofthe invention herein chosen for purposes of disclosure which do notconstitute departures from the spirit and scope of the inventiont 4 Whatis claimed is: The method of making diethoxyphosphoryltetramethyldiamidothiophosphate which comprises heating togethersubstantially equimolecular proportions of di- 5 ethoxyphosphorylchloride and a short chain alkyl ester ofbis(dimethylamido)thiophosphate.

References Cited in the file ofthis patent UNITED STATES PATENTSKosolapofl Sept. 4, 1951 OTHER REFERENCES

